Gear making

ABSTRACT

Gear making machine of the type in which a workpiece undergoes continuous indexing rotation with respect to a rotating cutter, the cutter being rotated through a worm, the worm being mounted for translation along its axis to superimpose upon the indexing rotation of the cutter a differential cutter rotation related to the feed of a workpiece slide through a cutting cycle, including a rotationally driven cam mounted endwise of the worm to produce the worm translation in correspondence to the rise or fall of the cam.

United States Patent 1 Moncrieff 1 3,710,685 1 Jan. 16, 1973.

541' GEAR MAKING [75] Inventor: Alexander D. F. Moncriefi, Marion,

Mass.

[73] Assignee: Bird Island, Inc., Boston, Mass. 22 Filed: "July l5, 1971 i [21] Appl. No.: 162,866

[52] US. Cl ..90/3, 90/9.6 [51] Int. Cl. ..B23f 5/20 [58] Field of Search ..90/3, 4, 5, 9, 9.6

[56] References Cited UNlTED STATES PATENTS 2,857,819 10/1958 Wildhaber etal. ..90/5 1,797,227 3/1931 Fickett ..90/3

1,516,524 11/1924 Fellows ..1 ..90/3

Primary ExaminerGil Weidenfeld Att0rneyRobert E. Hillman [57] ABSTRACT Gear making machine of the type in which a workpiece undergoes continuous indexing rotation with respect to a rotating cutter, the cutter being rotated through a worm, the worm being mounted for translation along its axis to superimpose upon the indexing rotation of the cutter a differential cutter rotation related to the feed of a workpiece slide through a cutting cycle, including a rotationally driven cam mounted endwise of the worm to produce the worm translation in correspondence to the rise or fall of the cam 8 Claims, 5 Drawing Figures PATENTEU JAN 16 I973 SHEET 2 OF 2 FIG 4 GEAR MAKING BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to gear making machines of the type in which a workpiece undergoes continuous indexing rotation with respect to a rotating cutter, and a differential rotation is superimposed upon the indexing rotation of the cutter as the workpiece is fed through the cutting cycle. I

2. Description of the Prior Art Such a machine is described in US. Pat. application Ser. No. 844,925 filed by Paul Maker on July 25, 1969 now U.S. Pat. No. 3,595,130. In that application, the differential cutter rotation is related to workpiece feed through a lever extending between the workpiece slide are rotated.

SUMMARY OF THE INVENTION In general the invention features a rotationally driven cam mounted endwise of the worm to produce translation of the worm in correspondence to the rise or fall of the cam, the differential rotation of the cutter thus being wholly dependent upon the shapeof the cam. In preferred embodiments the cam is carried on a shaft extending transversely to a wonn-carryingshaft to adjacent the workpiece slide, mechanical linkage being provided between the cam-carrying shaft and the slide to control the rate of slide feed in accordance with rotation of the cam-carrying shaft; the mechanical linkage includes a face cam carried adjacent the slide on the same shaft that carries the other cam, and a lever pivotal about an axis parallel to the axis of the wormcarrying shaft and having arms respectively bearing against the face cam and the slide; one of the lever arms has an adjustable portion to vary its effective length,

BRIEF DESCRIPTION OF-THE DRAWINGS FIG. 1 is a plan view partially in section of a fragment of a gear making machine;

FIG. 2 is an enlargement, further sectioned, of a ment of FIG. 1; I

FIG. 3 is a side elevation, partially in section, of the machine of FIG. 1;

FIG. 4 is a side elevation of a portion of the machine fragof FIG. 3, with the workpiece slide in a more forward.

position; and

FIG. 5 is an enlargement, further sectioned, of a fragment of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, workpiece slide 10 is mounted on frame 12 for linear translation relative. to cutters 14 and 16. Motor 18 rotates workpiece 20 through splined shaft 22, and rotates cutters 14 and 16 through worms 24 and 26 on shaft 28, these rotations occurring at basic indexing rates so long as slide 10 is stationary. Shaft 28 is mounted to permitits translation along its own axis 30, for imparting to the cutters differential rotation so that the teeth of the gear being made will have the desired profiles. In these and other respects unnecessary to detail here the machine is, with the exception of the improvement to be described, in substance the same as that described in the aboveidentified application, the disclosure of which is incorporated herein by reference.

Shaft 40 is mounted for rotation about axis 42 parallel to the direction of workpiece feed, driven by adjustable speed hydraulic motor-44 through worm 46 and worm gear 48. Shaft 40 extends along the side of the machine from justforward of slide 10 to adjacent shaft 28, andhas mounted on its cam 50 and plate cam 52.

Shaft 28 is biased toward cam 52 by hydraulic cylinder 54 mounted on frame 12 at the end of the shaft assembly opposite the cam. The shaft assembly bears against adjustable length element 56 mounted to slide in bearing block 57 fixed to frame 12, and comprising a nut 58 (FIG. 2) contacti'ngthe shaft assembly and a screw 60 threaded inside nut 58 and contacting operative cam surface 64 through carbide button 62. End portion 61 of screw 60 is of rectangular cross-section and passes through a rectangular opening in retaining bar 65 fixed to frame 12, to prevent rotation of screw 60. -Worm gear 66 is splined to nut 58 and is arranged to be rotationally adjusted by worm 67 carried by manually operable rod 68. Rotation of rod 68 thus causes rotation of nut 58 relative to screw 60, changing the length of element 56 and hence the initial position of shaft 28 in the cutting cycle, thus controlling the initial phase angle between the cutters and hence the tooth thickness of the gear being made.

Lever shaft 70 (FIG. 1), with its axis 72 parallel to axis 30 of shaft 28, extends through the wall of. frame 12 near slide 10, and has fixed to its ends, respectively (see especially FIG. 3), outside lever arm 74 and inside lever arm 76.

At the top of arm 74 (FIG. 5) cam-following roller 78 is mounted on vertically adjustable block 80, and bears against the operative surface 82 (that surface being generally transverse to axis 42) of cam 50.

Hydrostatic bearing 84 bears against the back of cam. 50 opposite roller 78 to prevent cam deflection. Hydraulic cylinder 86' biases arm 74 toward cam 50.

At'the top of lever arm'76 carbide button 90 bears against another carbide button 92'fixed to bracket extension 94 at the front of slide 10. Hydraulic cylinder 96, mounted on the underside of slide 10 with its piston rod coupled to arm 76 through straps 97 (the straps being pivotally connected to both the piston rod and arm 76), acts during the cutting cycle to hold slide 10 against arm 76 (FIG. 4). (Cylinder 96 also provides the rapid in and out (FIG. 3) motion of the slide during the loading and unloading cycle, as described in the aboveopposite ends face forward during the infeed and reversing the slide motion during the outfeed. The rate of translation of the slide (for a given rate of rotation of shaft 40) is determined by the shape of cam surface 82 and the ratio of the effective lengths of arms 74 and 76 (that ratio, and hence the generating circle radius of the gear being made, being subject to fine adjustment by raising or lowering block 80). At the same time, the rate of translation of shaft 28 along its axis 30 (and, hence, the differential rate of cutter rotation) is determined solely by the shape of cam surface 64 (for a given rate of rotation of shaft 40). Thus, e.g., to finish unmodified involute profiles during the outfeed requires differential cutter rotation linearly related to the workpiece feed rate; hence the radius of the portion of cam surface 64 that contacts button 66 during the outfeed must change at a rate (per degree of cam rotation) linearly related tothe corresponding rate of change of the height of surface 82. Similarly, non-linear relationships between surfaces 64 and 82 can produce non-involute profiles, infeed roughing, or the like, following the general principles of cutter phase control taught in the above-identified application.

Other embodiments arewithin the following claims. What is claimed is: 1. ln gear making apparatus comprising a cutter being rotatably mounted, means mounting a work piece for a predetermined rate of rotation with respect -worm axis, to determine tooth means supporting said worm for translation along its axis to superimpose upon the rotation of the cutter a differential cutter rotation, means regulating the differential cutter rotation in relation to the linear feed rate of said slide means during a cutting cycle, said regulating means including a rotationally driven cam mounted endwise of said worm supporting means and cooperating therewith to produce said translation in correspondence to the shape of the cam.

2. The improvement of claim 1 wherein said cam is carried on a shaft extending transversely to theworm axis to adjacent the workpiece slide means, mechanical linkage being provided between said shaft and the slide means to control the rate of slide means feed in accordance with rotation of said shaft.

3 The improvement of claim 2 wherein said mechanical linkage includes a second cam carried on said shaft.

4. The improvement of claim 3 wherein said second cam has its operative cam surface transverse to the axis of said shaft.

5. The improvement of claim 2 wherein said mechanical linkage includes a lever having a pivot axis parallel to the worm axis.

6. The improvement of claim 5 wherein a second cam is mounted for rotation adjacent the slide means and said lever has arms respectively bearing against the slide means and said second cam.

7. The improvement of claim 2 wherein said mechanical linkage includes a lever having a portionv adjustable to vary the effective lever arm ratio thereby to determine the generating circle radius of the gear being made.

8. Theimprovement of claim 1 wherein the worm is mounted on a shaft coupled to a cam-following member adjustable with respect tothe worm along the thickness in the gear being made.

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1. In gear making apparatus comprising a cutter being rotatably mounted, means mounting a work piece for a predetermined rate of rotation with respect to said rotatable cutter, a worm drivingly associated with said cutter for rotating same, slide means for linearly feeding the work piece relative to said cutter, means supporting said worm for translation along its axis to superimpose upon the rotation of the cutter a differential cutter rotation, means regulating the differential cutter rotation in relation to the linear feed rate of said slide means during a cutting cycle, said regulating means including a rotationally driven cam mounted endwise of said worm supporting means and cooperating therewith to produce said translation in correspondence to the shape of the cam.
 2. The improvement of claim 1 wherein said cam is carried on a shaft extending transversely to the worm axis to adjacent the workpiece slide means, mechanical linkage being provided between said shaft and the slide means to control the rate of slide means feed in accordance with rotation of said shaft.
 3. The improvement of claim 2 wherein said mechanical linkage includes a second cam carried on said shaft.
 4. The improvement of claim 3 wherein said second cam has its operative cam surface transverse to the axis of said shaft.
 5. The improvement of claim 2 wherein said mechanical linkage includes a lever having a pivot axis parallel to the worm axis.
 6. The improvement of claim 5 wherein a second cam is mounted for rotation adjacent the slide means and said lever has arms respectively bearing against the slide means and said second cam.
 7. The improvement of claim 2 wherein said mechanical linkage includes a lever having a portion adjustable to vary the effective lever arm ratio thereby to determine the generating circle radius of the gear being made.
 8. The improvement of claim 1 wherein the worm is mounted on a shaft coupled to a cam-following member adjustable with respect to the worm along the worm axis, to determine tooth thickness in the gear being made. 